Salmon Can Again PassLittle Goose Dam

Fish move up ladders after operatorscut the volume of water flow spilled over the dam during the daytime

Dam operators appear to have fixed the problem that blocked adult salmon from heading upriver for several days at Little Goose Dam on the Snake River.

All but a few fish abruptly stopped moving over fish ladders at the dam on June 20, when federal operators began spilling a large volume of river flow over Little Goose and two other Snake River dams in a court-ordered measure meant to help juvenile fish move downstream.

At Little Goose -- but no other dams -- eddying water generated by the spill appears to have prevented salmon from following the guiding flow of water over fish ladders. Industry groups were quick to seize on the unexpected problem last week as evidence that the spill plan was ill-advised. Irrigators and utilities in particular opposed the spill plan because of the costs -- an estimated $57 million to $81 million in foregone power generation.

Dam operators first tried to change the pattern of flow over spillways, and when that failed they severely cut back the volume of water spilled during daylight hours when salmon are moving upriver, which did the trick. The number of fish passing jumped tenfold June 30 from the previous day, most of the fish moving in the first eight hours after spill was cut back to 30 percent of river flow, according to the U.S. Army Corps of Engineers.

An analysis by the Portland-based Fish Passage Center this week concluded that reducing daytime spill fixed the problem, and that delayed passage and adult survival at Little Goose "does not at this time appear to be an issue," said center director Michelle DeHart, in a Thursday memo.

Federal agencies, meanwhile, continue an appeal of the court order, arguing that the additional spill still could worsen the survival chances of juvenile salmon left exposed to slower and hotter summer river conditions. The National Marine Fisheries Service, the federal agency responsible for threatened and endangered salmon, endorsed a plan to collect most of the summer-migrating Snake River salmon and transport them by barge and truck past the dams.
The 9th U.S. Circuit Court of Appeals hears arguments Wednesday and has promised a speedy ruling.